The Seven Lucky Gods are (except for one) based on deities of nearby cultures and have become popular patrons of different professions and virtues. The book gives a long list of professions that each god supports. Here is a brief summary of the seven:
Benten, or Benzaiten, is the goddess of art, knowledge, and beauty. She wears a flowing dress and holds a biwa (Japanese flute). She is similar to the Hindu goddess Sarasvati (who would be my favorite deity if I were Hindu.
Ebisu is the god of wealth, fair trading, and good fortune, and is considered an indigenous Japanese deity. He often holds a fishing rod.
Hotei is the god of good health and guardian of children, and also of magnanimity and good fortune.
When people erroneously think of Buddha (Siddhartha) as a little fat and bald, happy man, they are actually thinking of Hotei, who is based on the 10th century zen priest Kaishi.
Bishamon, or Bishamonten, is the defender against evil and protector of warriors. He is depicted as an armed warrior in armor.
Daikoku, or Daikokuten is the god of commerce, trade, and wealth, commerce and trade. He is depicted as a smiling man, holding a mallet. Interestingly, he may have originally been a deity of death like the Hindu god Mahakala.
Fukurokuju is the god of longevity, wealth, and happiness. He may have originally been a Dao god, or perhaps Confucius' disciple Roshi. Fukurokuju has an elongated forehead and a moustache, and holds a walking stick with a scroll. He is the only god of the seven to have power to revive the dead.
Jurojin is also a deity of longevity, as well as wisdom. He is an old, white-bearded man who wears a hate and carries a walking stick with a scroll.
My book indicates that the gods ride in a magic boat called the Takarabune, and they travel in this treasure ship from heaven to human ports each New Year's Eve. A person might place a picture of the gods under his or her pillow and, if the person dreams about the gods (and does not tell anyone about the dream), he or she will have good fortune for the year. The earliest mention of the Seven Lucky Gods as a group dates to the 15th century, in Fushimi.